 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.part;

 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Layout;

 /**
  * A pagebook is a composite control where only a single control is visible
  * at a time. It is similar to a notebook, but without tabs.
  * <p>
  * This class may be instantiated; it is not intended to be subclassed.
  * </p>
  *
  * @see PageBookView
  */
 public class PageBook extends Composite {

     /**
      * <p>
      * [Issue: This class should be declared private.]
      * </p>
      */
     public class PageBookLayout extends Layout {

         protected Point computeSize(Composite composite, int wHint, int hHint,
                 boolean flushCache) {
             if (wHint != SWT.DEFAULT && hHint != SWT.DEFAULT) {
                 return new Point(wHint, hHint);
             }

             Point result = null;
             if (currentPage != null) {
                 result = currentPage.computeSize(wHint, hHint, flushCache);
             } else {
                 //Rectangle rect= composite.getClientArea();
 //result= new Point(rect.width, rect.height);
 result = new Point(0, 0);
             }
             if (wHint != SWT.DEFAULT) {
                 result.x = wHint;
             }
             if (hHint != SWT.DEFAULT) {
                 result.y = hHint;
             }
             return result;
         }

         protected void layout(Composite composite, boolean flushCache) {
             if (currentPage != null) {
                 currentPage.setBounds(composite.getClientArea());
             }
         }
     }

     /**
      * The current control; <code>null</code> if none.
      */
     private Control currentPage = null;

     /**
      * Creates a new empty pagebook.
      *
      * @param parent the parent composite
      * @param style the SWT style bits
      */
     public PageBook(Composite parent, int style) {
         super(parent, style);
         setLayout(new PageBookLayout());
     }

     /**
      * Shows the given page. This method has no effect if the given page is not
      * contained in this pagebook.
      *
      * @param page the page to show
      */
     public void showPage(Control page) {

         if (page == currentPage) {
             return;
         }
         if (page.getParent() != this) {
             return;
         }

         Control oldPage = currentPage;
         currentPage = page;

         // show new page
 if (page != null) {
             if (!page.isDisposed()) {
                 page.setVisible(true);
                 layout(true);
                 // if (fRequestFocusOnShowPage)
 // page.setFocus();
 }
         }

         // hide old *after* new page has been made visible in order to avoid flashing
 if (oldPage != null && !oldPage.isDisposed()) {
             oldPage.setVisible(false);
         }
     }
 }

